1. Field of the Invention
Embodiments of the present disclosure pertain to mechanically reinforced polymer compositions and, in particular, to systems and methods for preparing dispersions of core shell rubber particles in polymer compositions such as epoxy resins.
2. Description of the Related Art
Thermoset polymer matrices, such as epoxies, are used extensively in a variety of retail and commercial products, owing to their good combination of mechanical and chemical properties (e.g., strength, glass transition temperature, modulus, resistance to chemical attack, etc.). A thermoset epoxy network may be formed from two different chemical compounds, referred to as a resin and a hardener. The resin may comprise monomers or short chain polymers having an epoxide group at either end, while the hardener may comprise compounds including a nitrogen atom linked to two hydrogen atoms (e.g., an amine group, —NH2). The lone pair of electrons from the nitrogen attacks the epoxy group, leaving active hydrogen from the amine to form ether linkages, cross-linking the material, giving the epoxy its strength.
Unfortunately, cured epoxy resins typically exhibit brittle fracture. For example, epoxies exhibit poor fracture toughness (e.g., less than about 1 MPa m1/2), poor resistance to crack propagation, and low impact strength. Planes of weakness may arise from the structuring of the highly cross-linked material and fracture propagates easily along these planes. The higher the cross-link density of the material, the less likely plastic deformation will occur and the more likely the epoxy material will be susceptible to crack propagation and catastrophic failure. This relatively low resistance to fracture and impact limits the application of epoxies.